Recently, use of conductive molded plastic products is increasing in households, industrial fields, offices, etc. and the demand is gradually expanding especially in electronic goods. Conductive molded plastic products can be applicable in many fields such as touch panels, EL back lights, shields from electromagnetic waves, antistatic products, solar cells, radiation of heat, car window covers, fabrics, etc. Also molded plastic products to shield from electromagnetic waves are in the spotlight as materials because more people have an interest in maleficence of electromagnetic waves these days. Further, said molded plastic products are also used as materials for car in-mold films and building interior.
For example, hospitals use more expensive medical equipments producing a lot of electromagnetic waves. Therefore, development of molded plastic fabrics or wares with excellent conductivity such as electromagnetic waves shielding effectiveness and antistatic property is needed. On the other hand, indoor air pollution in hospitals is known to be a main cause for nosocomial infection. The influence of indoor air pollution in hospitals on newborn babies, elderly people and patients with weak immunity and resistance to pathogenic bacteria is significant. In general, 10˜20% of nosocomial infection is by aerial infection, while the rest are indirect infection by molded products such as articles and wares used in hospitals.
Molded products that can induce infection include patients' bedding, hospital gowns, hospital workers' duty uniforms, plastic wares, etc. It is known that the number of nosocomial infection is 2.8˜15.0% of inpatients. In order to reduce nosocomial infection, infection cases by fabrics and disposable plastic wares such as tubes, trays, components, etc. should be removed. That is why, development of plastic materials with excellent antibiosis necessary. In other words, molded plastic products used in hospitals should satisfy both conductivity to shield micromagnetic waves and antibiosis to prevent from nosocomial infection.
For improving conductivity of molded plastic products, Korean Patent Application No. 2012-7022202 improved anti-electrostaticity by applying divalent cation of group 2 elements and salt of phosphoric ester. In addition, Korean Patent Application Nos. 2011-7014670, 2010-0101700 and 2009-0098692 provided conductivity of plastic materials by using organic salt having fluorine group and sulfonyl group. Korean Patent Application No. 2009-7006733 improved conductivity of plastic materials by adding a highly polymerized compound having PEO chains as a conductive basic structure. As stated in the cited references, salt of phosphoric ester, organic salt having fluorine group and sulfonyl group, etc. are simply applied to plastic products while easily improving conductivity. However, the drawback with using warm water is that conductivity of plastic wares sharply decreases. In addition, in case of producing plastic wares by compounding conductive polymers having PEO chains, deformation occurs because of non-uniformed crystallinity and crystal size by part.
There are prior studies on antibiosis of molded plastic products. Korean Patent Application No. 10-0559405 compounded 10˜20 weight percent of sulfur powder having 1˜3 μm of particle size with resin, while Korean Patent Application No. 10-0766418 produced plastic products with excellent antibiosis by compounding 1˜600 nm silver nano powder and titanium dioxide with resin. Also Korean Patent Application No. 10-0987728 produced antibacterial yarn by depositing silver on the surface of resin using sputtering or ion plating, and then blending the deposited silver. Korean Patent Application No. 10-1180117 produced antibacterial yarn by dyeing zinc sulfide nano particles and organic antimicrobial.
However, there are a lot of limits to commercialization in spite that antibiosis of silver and sulfur ingredients used in the cited references is known to be excellent. Although silver has good antibiosis and convenience, its supply price is extremely high. In case of sulfur, there are several unsolved problems such as environmental problem, difficulties of manufacturing, etc. Also deposition or coating have low economic feasibility and efficiency as a method to get antibiosis.